Full depth drilling system and method

ABSTRACT

A system for drilling a cased wellbore includes a casing string and a drill bit coupled to the casing string, an end of the casing string being substantially aligned with an end of the drill bit. The system also includes a telescoping section formed in the casing string, the telescoping section having a variable length between a first open position and a second closed position, the first open position forming a longer overall casing string length than the second closed position.

BACKGROUND 1. Field of the Invention

The present disclosure relates to oil and gas drilling operations, andmore specifically, to full depth drilling systems, such as drilling withcasing systems.

2. Description of Related Art

During oil and gas exploration operations, a wellbore may be drilledinto a formation through or near a potential hydrocarbon-bearing region.Often, wellbores include casing to line the walls of the wellbore tostabilize pressure within the formation. Typical operations includedrilling a wellbore, installing casing, drilling through the casing,installing a slightly smaller diameter casing, and so on until a desireddepth is reached. Casing may be extended into the wellbore and attachedto an intermediate structure, such as a hanger, in certain instances.This process is time consuming and expensive. Other methods may includedrilling with casing, where a drill bit is coupled to a segment ofcasing, which enables installation of the casing during drilling.However, these systems may not be drilling to full depth. In otherwords, the wellbore is not drilled beyond a depth of the casing, whichis undesirable for subsequent casing installation.

SUMMARY

Applicants recognized the problems noted above herein and conceived anddeveloped embodiments of systems and methods, according to the presentdisclosure, for drilling operations.

In an embodiment, a system for drilling a cased wellbore includes acasing string and a drill bit coupled to the casing string, an end ofthe casing string being substantially aligned with an end of the drillbit. The system also includes a telescoping section formed in the casingstring, the telescoping section having a variable length between a firstopen position and a second closed position, the first open positionforming a longer overall casing string length than the second closedposition.

In another embodiment, a wellbore system includes a first casingpositioned within a wellbore, the first casing being secured to anunderground formation at a first landing location. The method alsoincludes a second casing, extending through a bore of the first casing,the second casing having a drill bit positioned at an end to extend aborehole formed downhole of the first casing. The second casing includesa first segment and a second segment, arranged radially outward from thefirst segment, at least a portion of second segment overlapping thefirst segment and the first and second segments being axially movablerelative to one another to adjust a second casing length. A secondcasing length is reduced after the borehole is extended to apredetermined location and the second casing is landed at a secondlanding location.

In an embodiment, a method for drilling a full depth wellbore includespositioning a first casing string in a wellbore at a first landinglocation. The method also includes positioning a second casing stringthrough the first casing string, the second casing string including adrill bit. The method further includes extending a borehole length, viathe drill bit, to a predetermined location. The method also includeslanding the second casing string at a second landing location, whereinthe borehole length extends beyond a second casing string end after thesecond casing string is positioned at the second landing location.

BRIEF DESCRIPTION OF DRAWINGS

The foregoing aspects, features, and advantages of the presentdisclosure will be further appreciated when considered with reference tothe following description of embodiments and accompanying drawings. Indescribing the embodiments of the disclosure illustrated in the appendeddrawings, specific terminology will be used for the sake of clarity.However, the disclosure is not intended to be limited to the specificterms used, and it is to be understood that each specific term includesequivalents that operate in a similar manner to accomplish a similarpurpose.

FIG. 1 is a schematic side view of an embodiment of an offshore drillingoperation, in accordance with embodiments of the present disclosure;

FIG. 2 is a schematic side view of an embodiment of a cased wellbore, inaccordance with embodiments of the present disclosure;

FIGS. 3A and 3B are schematic cross-sectional views of embodiments of acasing system including a telescoping section, in accordance withembodiments of the present disclosure;

FIGS. 4A-4F are schematic diagrams of embodiments of a telescopingsection, in accordance with embodiments of the present disclosure; and

FIG. 5 is a flow chart of an embodiment of a method for drilling awellbore using a casing system, in accordance with embodiments of thepresent disclosure.

DETAILED DESCRIPTION

The foregoing aspects, features, and advantages of the presentdisclosure will be further appreciated when considered with reference tothe following description of embodiments and accompanying drawings. Indescribing the embodiments of the disclosure illustrated in the appendeddrawings, specific terminology will be used for the sake of clarity.However, the disclosure is not intended to be limited to the specificterms used, and it is to be understood that each specific term includesequivalents that operate in a similar manner to accomplish a similarpurpose.

When introducing elements of various embodiments of the presentdisclosure, the articles “a”, “an”, “the”, and “said” are intended tomean that there are one or more of the elements. The terms “comprising”,“including”, and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements. Anyexamples of operating parameters and/or environmental conditions are notexclusive of other parameters/conditions of the disclosed embodiments.Additionally, it should be understood that references to “oneembodiment”, “an embodiment”, “certain embodiments”, or “otherembodiments” of the present disclosure are not intended to beinterpreted as excluding the existence of additional embodiments thatalso incorporate the recited features. Furthermore, reference to termssuch as “above”, “below”, “upper”, “lower”, “side”, “front”, “back”, orother terms regarding orientation or direction are made with referenceto the illustrated embodiments and are not intended to be limiting orexclude other orientations or directions.

Embodiments of the present disclosure include a telescoping section of atubular (e.g., pipe, casing, high pressure housing, etc.) that enablesselective collapse of a casing string. As a result, casing hangersand/or high pressure housing may be provided that are sturdy enough toachieve total depth while drilling, yet also allow sufficient weight toproperly land and lock into respective landing locations. Embodimentsmay save a return trip for the rig while drilling a wellbore andinstalling casing.

Embodiments of the present disclosure provide a telescoping joint in acasing string to provide a sufficient weight at a land out point. Astructural member contained within the telescoping joint providessufficient strength for drilling, yet collapses when setting theequipment. By way of example, the structural member may include shearpins, J-slots, dissolvable components, resilient members (e.g., springs,bellows), triggers, sliding sleeves, and the like.

FIG. 1 is a side schematic view of an embodiment of subsea drillingoperation 100. The drilling operation includes a vessel 102 floating onthe sea surface 104 substantially above a wellbore 106. It should beappreciated that the vessel 102 is shown for illustrative purposes only,and in various embodiments, other structures such as drilling platformsmay be utilized with embodiments of the present disclosure. Furthermore,subsea operations are also for illustration only and surface explorationmay also utilize embodiments of the present disclosure. A wellborehousing 108 sits at the top of the wellbore 106 and is connected to ablowout preventer (BOP) assembly 110, which may include shear rams 112,sealing rams 114, and/or an annular ram 116. One purpose of the BOPassembly 110 is to help control pressure in the wellbore 106. The BOPassembly 110 is connected to the vessel 102 by a riser 118. Duringdrilling operations, a drill string 120 passes from a rig 122 on thevessel 102, through the riser 118, through the BOP assembly 110, throughthe wellhead housing 108, and into the wellbore 106. The lower end ofthe drill string 120 is attached to the drill bit 124 that extends thewellbore 106 as the drill string 120 turns. It should be appreciatedthat while a drilling operation is illustrated, embodiments of thepresent disclosure may also be incorporated into logging operations,stimulation operations, recovery operations, and the like. Additionalfeatures shown in FIG. 1 include a mud pump 126 with mud lines 128connecting the mud pump 126 to the BOP assembly 110, and a mud returnline 130 connecting the mud pump 126 to the vessel 102. It should beappreciated that the illustrated mud pump 126 is at a subsea location,but in other embodiments, the mud pump 126 may be arranged on the vessel102. Moreover, in embodiments, the mud pump 126 may receive a mud supplyfrom a pit or mud shake on the vessel 102. A remotely operated vehicle(ROV) 132 can be used to make adjustments to, repair, or replaceequipment as necessary. Although the BOP assembly 110 is shown in thefigures, the wellhead housing 108 could be attached to other wellequipment as well, including, for example, a tree, a spool, a manifold,or another valve or completion assembly.

One efficient way to start drilling the wellbore 106 is through use of asuction pile 134. Such a procedure is accomplished by attaching thewellhead housing 108 to the top of the suction pile 134 and lowering thesuction pile 134 to a sea floor 136. As interior chambers in the suctionpile 134 are evacuated, the suction pile 134 is driven into the seafloor 136, as shown in FIG. 1, until the suction pile 134 issubstantially submerged in the sea floor 136 and the wellhead housing108 is positioned at the sea floor 136 so that further drilling cancommence. As the wellbore 106 is drilled, the walls of the wellbore arereinforced with steel casings 138 that provide stability to the wellbore108, and may also be cemented to the formation, and help to controlpressure from the formation.

During operations, such as drilling operations, mud is injected into thewellbore 106 via the drilling string 120. For example, the mud pump 126may receive drilling mud from the vessel 102 and direct the mud throughthe drill string 120. The mud flows through the drilling string 120 andexits at the drill bit 124, carrying rock cuttings away from the bit 124and also cooling the bit. The mud enters an annulus 140 surrounding thedrill string 120. Advantageously, this mud may be utilized to providepressure control within the wellbore 106, for example, to balancepressures from the formation. The mud may fill the wellbore 106 and theriser 118, where it is returned to the vessel 102 for processing andreuse.

While the illustrated embodiment shows drilling operations where casing138 is installed as a subsequent step, drilling with casing provides thebenefit of potential timesaving by not requiring an additional trip toinstall casing after a hole has been drilled. Typically, a hole isdrilled deeper than the expected depth of the casing to be installed andthen the bit is removed for subsequent casing installation. Onepotential solution is drilling with casing. However, in a subseawellhead, for example, sufficient weight for installation and properseating at respective landing locations is important. Drilling withcasing does not allow for a deeper hole than the length of the casingstring, thereby introducing potential problems trying to properly landequipment. Embodiments of the present disclosure overcome these problemsby incorporating the telescoping section having sufficient structuralstrength for drilling while also ensuring enough weight is availableduring landing of the equipment to achieve successful installation.

FIG. 2 is a cross-sectional side view of a cased wellbore 200. Asdescribed above, in various embodiments, wellbores may include sectionsof casing 202 that decrease in diameter. For example, a first casing202A may be positioned radially outward from a second casing 202B, whichis radially outward from both a third casing 202C and a fourth casing202D. In embodiments, cement 204 may be positioned between the casings.In this embodiment, a tubular 206 extends through the annulus 208 andmay include a drill bit 210. As shown, the drill bit 210 has an end 212that is substantially aligned with a tubular end 214. As a result,drilling will not extend beyond the tubular end 214. However, extendingthe borehole beyond the casing is often desirable for subsequentinstallation where weight may be utilized to proper set the casing. Aswill be described, embodiments of the present disclosure enable drillingbeyond the casing end, while also providing sufficient weight to set thecasing at respective landing locations.

FIG. 3A is a cross-sectional side view of an embodiment of a casingsection 300. The illustrated embodiment includes an outer casing 302,which may be preferred to as a low pressure casing and an inner casing304, which in this embodiment corresponds to a high pressure casing. Itshould be appreciated that embodiments may also be directed toward highand low pressure housing sections, as noted above. The illustratingcasing section 300 illustrates the outer casing 302 and the inner casing304 axially aligned along a wellbore axis 306, which the inner casing304 being arranged radially closer to the wellbore axis 306 than theouter casing 302.

In this embodiment, the outer casing 302 is a stationary component, forexample due to its position at a respective landing location 308, wherea top 310 is at a first location 312, represented by the broken line. Aswill be described below, the inner casing 304 may be axially movedrelative to the outer casing 302 when the inner casing 304 is set at arespective landing location. FIG. 3A illustrates a segment 314 of theinner casing 304 at a second location 316, represented by a broken line,which may correspond to a top of the inner casing 304 and/or to anotherlocation along the inner casing 304. As shown, a distance 318 separatesthe first location 312 and the second location 316.

The illustrated inner casing 304 includes a telescoping section 320,which is shown in an expanded or deployed position in FIG. 3A. As aresult, a casing length 322 is shown between the second location 316 anda string bottom 324. The telescoping section 320 includes a structuralmember 326 arranged within a void 328 formed between a first segment 330and a second segment 332. As will be described below, in operation, avoid length 334 is maintained during drilling operations and reducedwhen the inner casing 304 lands at a respective landing location,thereby enabling the inner casing 304 to collapse axially and reduce thecasing length 322.

In the illustrated embodiment, at least a portion of the first segment330 is overlapped by the second segment 332, with the first segment 330being positioned radially inward from the second segment 332 (e.g.,closer to the axis 306). In various embodiments, at least a portion ofthe first segment 330 and/or the second segment 332 may include anextension or a slot to facilitate coupling between the first and secondsegments 330, 332. For example, a tongue and groove fitting or tracksmay be arranged between the first and second segments 330, 332 tofacilitate coupling while maintaining freedom of axial movement. Thestructural member 326 may be coupled to or otherwise positioned withinthe void 328 to prevent movement or inadvertent collapse or the innercasing 304 during drilling operations. However, as will be describedbelow, once at a predetermined or desired position, the structure member326 may be collapsed or otherwise removed to facilitate furtheroperation. It should be appreciated that the structural member 326 maynot be positioned within the void 328 in all embodiments, and such anarrangement is described for illustrative purposes. For example, thestructural member may extend through the first and second segments 330,332, such as shears pins, or the like.

FIG. 3A may correspond to a drilling operation where the drill bit 210advances through the formation and past the outer casing 302. As shown,the inner casing 304 is positioned in an expanded position such that thecasing length 322 is longer than the casing length when in a collapsedposition, as will be described below. In certain embodiments, drillingmay continue beyond a respective landing location and/or to a landinglocation. The telescoping section 320 may then be activated to positionthe inner casing 304 in a desired orientation, as shown herein.

FIG. 3B is a cross-sectional view of the casing section 300 where theinner casing 304 is transitioned to the collapsed or set position suchthat the void 328 is gone or substantially gone. In other words, thevoid length 334 is approximately zero in the illustrated embodiment. Asshown, the inner casing 304 has shifted with respect to FIG. 3A suchthat the casing length 322 is shorter in FIG. 3B than in FIG. 3A.Furthermore, the distance 318 between the first location 312 and thesecond location 316 is decreased. In operation, the outer casing 302 mayremain in a fixed position as the inner casing 304 moves, such asmovement of the first segment 330 with respect to the second segment 332and/or movement of the second segment 332 with respect to the firstsegment 330.

In various embodiments, the inner casing 304 may transition to thecollapsed position based at least in part on a weight of the firstsegment 330, which facilitates setting the inner casing 304. Forexample, in embodiments, a shoulder 336 of the second segment 332 mayengage a second landing location, which may block continued downwardmovement of the second segment 332. A force may be applied, which may atleast partially incorporate the weight of the first segment 330, tofacilitate collapse of the telescoping section 320. As a result, thecasing and/or borehole may extend beyond the second landing location.

It should be appreciated that, in other embodiments, the casing landinglocation may be previously selected based on one or more properties ofthe drilling operation, such as formation properties, mud weight, andthe like. Accordingly, the inner casing 304 may be installed to thedesired location, and thereafter, activated to collapse the telescopingsection 320. In certain embodiments, activation may be driven by upholeactivities, such as closing in and pressuring the well, by the outercasing 302, or any other reasonable method. In this manner, the innercasing 304 may be set to continue with additional drilling and/orproduction operations.

Furthermore, it should be appreciated that, in various embodiments, theinner casing 304 may be actuated such that the bottom 324 is movedaxially upward (e.g., toward the surface), thereby providing additionaldrilled area axially lower than the end of the inner casing 304. Forexample, the inner casing 304 may be lifted and coupled to a casinghanger at an uphole location, or the casing hanger may be rotated inorder to couple to another uphole component.

FIGS. 4A-4F are schematic diagrams of embodiments of the telescopingsection 320 including various components, which may or may not beincorporated into the structural member 326, to facilitate operation. Itshould be appreciated that certain features may be combined into asingle embodiment and, therefore, illustration of the componentsseparately is not intended to indicate that features may not be utilizedtogether. Embodiments of the present disclosure may provide improvedstrength and stability for the telescoping section 320 during drillingoperations while also selectively collapsing to enable full depthdrilling with casing. As noted above, various embodiments may facilitateaxially downward movement of the first segment 330 and/or axially upwardmovement of the second segment 332.

FIG. 4A is a cross-sectional view of an embodiment of the telescopingsection 320 including shear pins 400 extending through the first segment330 and the second segment 332. It should be appreciated that theillustrated pair of shear pins 400 is for illustrative purposes only andthere may be more or fewer shear pins 400 in other embodiments. Theillustrated shear pins 400 may provide structural stability duringdrilling operations by securing movement between the second segment 332and the first segment 330. However, upon activation of the inner casing304, a force may be applied to break the shear pins 400 and facilitatecollapse of the void 328, thereby moving the first segment 330 axiallydownward and/or moving the second segment 332 axially upward.

Further illustrated in FIG. 4A is a blocking shear pin 402 which doesnot extend through the first segment 330. As an example, the blockingshear pin 402 is positioned within the void 328 and blocks movement ofthe first segment 330 in an axially downward direction. However,sufficient force may break the blocking shear pin 402, thereby drivingthe first segment 330 into the void 328.

FIG. 4B is a cross-sectional view of an embodiment of the telescopingsection 320 including a dissolvable component 404 arranged within thevoid 328. The dissolvable component is formed from a material that hasstructural rigidity and/or certain properties until being exposed tocertain fluids or compounds. Moreover, the dissolvable material may beany material configured to dissolve in the presence of a certain fluid,for a certain amount of time, at a certain temperature, or anycombination thereof. For example, the dissolvable material may startdissolving when exposed to a predetermined temperature and/or apredetermined fluid, such as wellbore fluid. By way of example, thedissolvable material may be or include a magnesium, thermoplastic,dissolvable aluminum, a water soluble, synthetic polymer compositionincluding a polyvinyl, alcohol plasticizer and mineral filler, or acombination thereof. In other embodiments, the dissolvable material maybe a matrix of two or more materials. The first material of the matrixmay be configured to dissolve at a first rate and a second material maydissolve at a second rate.

In the illustrated embodiment, the dissolvable component 404 fillssubstantially all of the void 328. However, it should be appreciatedthat the dissolvable component 404 may be formed in any reasonable shapeand fill only a portion of the void 328. Accordingly, in operation, theinner casing 304 may be set at a certain location and then exposed toone or more dissolving conditions, noted above. When the dissolvablecomponent disintegrates and is removed from the void 328, the innercasing 304 may be set at the landing location as the void 328 collapses.

FIG. 4C is a side view of an embodiment of the telescoping section 320including a J-slot 406 to facilitating collapse of the void 328. In theillustrated embodiment, the J-slot 406 includes an extension 408extending off the first segment 330 and a slot 410. The extension 408 ispositioned within the slot 410 and, in operation, rotation mayfacilitate collapse of the void 328. For example, rotation may drive theextension 408 through the slot 410 in the direction of the arrows,thereby facilitating collapse in the axial direction.

FIG. 4D is a cross-sectional view of an embodiment of the telescopingsection 320 including a resilient member 412 positioned within the void328. The resilient member 412 may include a spring or bellows thatblocks collapse of the void 328 absent a force or pressure that exceedsthreshold quantity. Accordingly, upon positioning the inner casing 304at the desired location, a sufficient force to overcome the resilientmember 412 may be applied, thereby setting the inner casing 304.

FIG. 4E is a cross-sectional view of an embodiment of the telescopingsection 320 including a trigger or activator 414 that interacts with theouter casing 302 to facilitate collapse of the void 328. In thisembodiment, the activator 414 is coupled to a structural body 416. Uponactivation, the structural body 416 may be pivoted and move into a slotformed in the first segment 330, thereby enabling collapse of the void328.

FIGS. 4F is a cross-sectional view of an embodiment of the telescopingsection 320 including the trigger or activator 414. In this embodiment,a vessel 418 is positioned within the void 328, which may include apressurized fluid within resilient walls. Upon activation, an opening420 in the vessel 418 may facilitate outward flow of the fluid, therebyleading to collapse of the void 328.

FIG. 5 is an embodiment of a flow chart of a method 500 for drilling acased wellbore. It should be appreciated that this method, and othermethods described herein, may include more or fewer steps. Furthermore,the steps may be performed in a different order and/or may be performedin parallel, unless otherwise specifically stated. In this example, aportion of a wellbore is formed in a formation 502. The portion mayinclude a first section of casing, which may be secured to the formationvia cement or the like. A second section of casing is tripped into thewellbore along with a drill bit, which may be referred to as performinga portion of a casing while drilling operation. A hole, formed byoperation of the drill bit, is extended into the formation to a locationbeyond an end of the first section of casing 504. In variousembodiments, a telescoping section of the second section of casing isactivated 506. As described above, activating the telescoping sectionmay include collapsing a void within the telescoping section. The secondsection of casing is then landed at a landing location, for example,using a weight from above 508. In this manner, casing may be installedduring drilling operations, which may save trips out of the wellbore toretrieve casing, thereby reducing rig time.

The foregoing disclosure and description of the disclosed embodiments isillustrative and explanatory of the embodiments of the invention.Various changes in the details of the illustrated embodiments can bemade within the scope of the appended claims without departing from thetrue spirit of the disclosure. The embodiments of the present disclosureshould only be limited by the following claims and their legalequivalents.

1. A system for drilling a cased wellbore, comprising: a casing string;a drill bit coupled to the casing string, an end of the casing stringbeing substantially aligned with an end of the drill bit; and atelescoping section formed in the casing string, the telescoping sectionhaving a variable length between a first open position and a secondclosed position, the first open position forming a longer overall casingstring length than the second closed position.
 2. The system of claim 1,wherein the telescoping section comprises: a first segment of casingstring; a second segment of the casing string, the second segmentarranged radially outward from the first segment and at least partiallyoverlapping the first segment; and a void between an end of the firstsegment and the second segment, wherein a void length between the end ofthe first segment and the second segment is greater in the first openposition than in the second open position.
 3. The system of claim 2,wherein the first segment moves into the void when the telescopingsection transitions to the second closed position.
 4. The system ofclaim 1, wherein the telescoping section further comprises: a structuralmember maintaining the first open position.
 5. The system of claim 4,wherein the structural member comprises a dissolvable component.
 6. Thesystem of claim 4, wherein the structural member comprises a shear pin.7. The system of claim 1, wherein the telescoping section furthercomprises a j-slot, comprising: an extension extending from a radiallyinward portion of the casing string; and a slot formed in a radiallyoutward portion of the casing string, the extension moving through theslot in response to rotation of at least a portion of the casing string.8. A wellbore system, comprising: a first casing positioned within awellbore, the first casing being secured to an underground formation ata first landing location; a second casing, extending through a bore ofthe first casing, the second casing having a drill bit positioned at anend to extend a borehole formed downhole of the first casing, the secondcasing comprising: a first segment; and a second segment, arrangedradially outward from the first segment, at least a portion of secondsegment overlapping the first segment and the first and second segmentsbeing axially movable relative to one another to adjust a second casinglength; wherein a second casing length is reduced after the borehole isextended to a predetermined location and the second casing is landed ata second landing location.
 9. The wellbore system of claim 8, wherein atleast a portion of the first segment and at least a portion of thesecond segment forms a telescoping section of the second casing.
 10. Thesystem of claim 9, wherein the telescoping section further comprises: astructural member arranged between the first segment and the secondsegment, the structural member maintaining an extended second casinglength during a drilling operation.
 11. The system of claim 10, whereinthe structural member is configured to disengage to facilitate movementbetween the first segment and the second segment to form a collapsedsecond casing length.
 12. The system of claim 10, wherein the structuralmember comprises a dissolvable component.
 13. The system of claim 10,wherein the structural member comprises a shear pin.
 14. The system ofclaim 10, wherein the structural member comprises a resilient member.15. The system of claim 10, wherein the second casing further comprises:an extension extending from the first segment; and a slot formed in thesecond segment, the extension moving through the slot in response torotation of at least a portion of the second casing string.
 16. Thesystem of claim 10, wherein engagement between the first casing and thesecond casing drives axial movement of the first segment and the secondsegment relative to one another.
 17. A method for drilling a full depthwellbore, comprising: positioning a first casing string in a wellbore ata first landing location; positioning a second casing string through thefirst casing string, the second casing string including a drill bit;extending a borehole length, via the drill bit, to a predeterminedlocation; and landing the second casing string at a second landinglocation, wherein the borehole length extends beyond a second casingstring end after the second casing string is positioned at the secondlanding location.
 18. The method of claim 17, further comprising:collapsing a telescoping section of the second casing string.
 19. Themethod of claim 18, wherein collapsing the telescoping section of thesecond casing string comprises: disengaging a structural member of thesecond casing string; and axially moving a first segment of the secondcasing string and a second segment of the second casing string relativeto one another, the movement reducing a second casing string length. 20.The method of claim 19, wherein the structural member comprises at leastone of a shear pin, a dissolvable component, a resilient member, or aj-slot.